Search

Numerical and regression modelling of 21 undamaged, fire-damaged and repaired fire-damaged circular reinforced concrete (RC) columns was undertaken. The columns were exposed to temperatures of 300°C, 500°C and 900°C and tested for axial residual capacity. It was found that the concrete lost strength after exposure to a temperature of 300°C or above. Fire-damaged columns were then repaired using various composite confinement techniques. Strength was regained when carbon-fibre-reinforced polymer (CFRP) confinement was applied to the fire-damaged columns but it also increased the deformation and thus reduced the stiffness, which is undesirable. As an alternative, steel wire mesh, filled with cement–sand mortar and wrapped with CFRP was employed. A numerical model to predict the residual capacity of these columns was developed. The development of numerical techniques, including material properties, geometry, elements, loading, boundary conditions and contact algorithms for undamaged, fire-damaged and repaired fire-damaged columns is reviewed and summarised. Analytical equations were developed using linear, multiple and quadratic regression modelling. The results obtained using the proposed model and regression equations showed that these models offer a better alternative to experimental testing for the prediction of the post-fire performance of damaged and repaired RC columns. [ABSTRACT FROM AUTHOR]

The torsional strengthening of reinforced concrete hollow beams (RCHBs) with externally bonded stainless steel wire mesh (SSWM) was investigated. The experimental programme involved casting and testing eight RCHBs of length 1300 mm and 150 mm × 150 mm cross-section with a 50 mm × 50 mm square hollow section in the centre. The beams were reinforced with 4–10 mm dia. longitudinal bars and 8 mm dia. stirrups at 150 mm centre to centre. Two unstrengthened RCHBs were designated as control specimens and the other six beams were strengthened using three different SSWM wrapping configurations. The test results were analysed based on torque–twist behaviour and the influence of SSWM on cracking torque, ultimate torque and failure modes. A numerical model was developed to predict the behaviour of RCHBs using the finite-element (FE) software Abaqus. The predictions of peak torque and corresponding twist obtained from the FE modelling showed good agreement with the experimental results. Based on the outcomes of this study, SSWM can be considered a feasible material for the torsional strengthening of reinforced concrete elements. [ABSTRACT FROM AUTHOR]

Reinforced concrete RC is a versatile and durable building material widely used in construction. This study investigated the impact of PVC-coated steel wire mesh layers on the compressive strength of RC. Seven cube specimens (70 × 70×70 mm) with varying numbers of PVC-coated layers were tested after a 28-day curing period. Results showed that specimens with two layers of PVC coating exhibited the highest ultimate compression stress and breaking force, indicating a significant 38% increase in compressive strength compared to those without PVC coating. The findings suggest that PVC-coated steel wire mesh provides a sustainable and costeffective method for reinforcing RC structures. By mechanically enhancing these structures, their overall mechanical properties can be improved. This research highlights the potential of PVC-coated steel wire mesh as an effective reinforcement technique, offering practical solutions for strengthening concrete structures. [ABSTRACT FROM AUTHOR]

• A total of fifteen one-way slabs were tested in four-point bending scheme. • Nine slabs were strengthened with ferrocement jackets, three were strengthened with CFRP, and two were strengthened with GFRP jackets. • The study focused on preventing debonding of the strengthening layers, employing either mechanical or chemical anchors. • The use of chemical anchors demonstrated a superior ability to delay debonding and enhance ductility compared to mechanical anchors. • The orientation of the wire mesh also played a crucial role, with parallel orientation to the longitudinal axis of slabs yielding better performance. Existing research lacks focus on the structural behavior of reinforced concrete (RC) one-way slabs reinforced with ferrocement, and there's a notable absence of comparative studies between fiber-reinforced polymers (FRPs) and ferrocement strengthening methods for these slabs. Given the cost-effectiveness and widespread use of ferrocement in structural reinforcement, this study aimed to address these gaps through an experimental program. Three sizes of wire mesh, categorized as Type-I (small), Type-II (medium), and Type-III (large), were employed in this study. Chemical or mechanical anchors were used to attach ferrocement jackets. Moreover, 6, 12, or 18 anchors were used to assess the effect of anchor configuration. The goal was to enhance the structural performance of slabs and compare them with slabs reinforced using FRP jackets. The study focused on preventing debonding of the strengthening layers, employing either mechanical or chemical anchors. All slabs exhibited ductile failure with flexural cracks. The peak load and ultimate deflection were enhanced by up to 49.00% and 109.07%, respectively, by the application of ferrocement jackets, whereas the dissipated energy was increased by up to 174.00 %. Notably, the use of chemical anchors demonstrated a superior ability to delay debonding and enhance ductility compared to mechanical anchors. Slabs reinforced with glass FRP (GFRP) showed delayed debonding relative to carbon FRP (CFRP) reinforced slabs, indicating the superior performance of chemical anchors with GFRP layers. Moreover, the type and size of wire mesh significantly influenced performance, with small and medium-sized mesh configurations enhancing ductility, while large-sized mesh exhibited relatively earlier debonding. The orientation of the wire mesh also played a crucial role, with parallel orientation to the longitudinal axis of slabs yielding better performance. [ABSTRACT FROM AUTHOR]

The infill walls may lose their positive effects during the first stages of earthquakes, either by leaving their plane or through breakage. That is why it is common to strengthen these walls before design earthquakes or to repair and strengthen them after suffering slight or moderate damage due to the occurrence of an earthquake. In this study, the effects of adding and strengthening these walls on the structural behavior of reinforced concrete structures were investigated. For this purpose, the infill walls were strengthened with a single mesh of reinforcement and covered with plaster. Five one-story, single bay, and ½ scaled reinforced concrete frames were cast: one was built without infill, the second with a bare infill wall, and the other three with strengthened infill walls with anchorage of different diameters. All these specimens were tested under cyclic loading type reverse. The tests resulted in important relationships and curves, including the lateral load-lateral displacement, envelope curve-lateral load, and lateral displacement, as well as stiffness-lateral displacement and others. Through these results, the effects of adding infill walls and the strengthening procedure of these walls on the structural behavior of the structures were discussed. [ABSTRACT FROM AUTHOR]

A new mechanical model of polyvinyl alcohol fiber–reinforced ferrocement cementitious composite (PVA-RFCC) was proposed with excellent integrated mechanical properties, which was reinforced with both PVA fiber and steel wire mesh (SWM). A series of experiments were conducted to study their mechanical properties, and a comparative analysis was also performed to evaluate their flexural toughness. The specimens of the PVA-RFCC thin plates were subjected to 4-point flexural experiments until their ultimate failure. The experimental results showed that the flexural properties of the PVA-RFCC specimens can be markedly improved compared with PVA-ECC (PVA-engineered cementitious composites) specimens. The highest increments in the initial stiffness, cracking strength, displacement ductility coefficient, and toughness of the PVA-RFCC specimens were improved by 62.4%, 174.7%, 251.0%, and 192.5%, respectively. The comparative analysis indicated that the method based on recent Chinese standards was suitable for the flexural toughness evaluation of the PVA-RFCC thin plates. A mechanical model of the PVA-RFCC thin plates was proposed. The PVA fibers had excellent prepeak behavior and the SWM had excellent postpeak behavior in the proposed mechanical model of the PVA-RFCC specimens. [ABSTRACT FROM AUTHOR]

Introducing fibers into concrete aims to improve the low tensile strength of concrete and its brittle properties. In this research, readily available PVC coated welded wire mesh with diameter of 1 mm was used as fibers in concrete. There are several variations of concrete samples prepared for this study, i.e. based on the fiber's volume fraction, length and interlocking schemes. Concrete samples were subjected to tensile and compressive strength, and elastic modulus tests. The results show that the incorporation of PVC coated welded wire mesh slightly increases the tensile strength of concrete, with the optimum fiber volume fraction of 1.5%; with the fiber length of 3.6 cm, and with the interlocking of 1.2 cm. However, the concrete compressive strength is slightly reduced, compared to the normal ones. The presence of PVC coated welded wire mesh as fiber also tends to reduce the elastic modulus of fiber reinforced concrete. [ABSTRACT FROM AUTHOR]

This experimental research aims to evaluate the impact resistance of the crimped wire mesh‐ and steel fiber‐reinforced concrete panels that receive the impact load of the high‐velocity projectile. The concrete panel's impact resistance was evaluated by using variables such as the steel fiber volume fraction, presence of crimped wire‐mesh reinforcement, thickness of panel, impact velocity, and the size of aggregates. The impact resistance was evaluated by using the nondimensional impact factor where various variables could be integrated. Although the improvement of the impact resistance particularly regarding its penetration depth caused by the steel fiber mix was insufficient, there was a visible effect of improvement in impact resistance for scabbing and perforation. This occurred as the steel fiber had a bridging effect within the concrete matrix. Moreover, when reinforced with crimped wire mesh, the area loss of the front and rare face decreased. While it was effective for perforation and scabbing, it was insufficient for improving the resistance of penetration. Meanwhile, there were some cases where a splitting bond failure occurred along the cover of the rear face in a few specimens. The outcomes suggest that if steel fibers are mixed with the wire mesh‐reinforced concrete panels, this, in turn, increases the splitting bond strength based on a bridging effect, thereby preventing a splitting bond failure. [ABSTRACT FROM AUTHOR]

• Anti-falling protection systems for existing floors of reinforced concrete and bricks. • Full-scale experimental tests up to failure on galvanised electro-welded steel wire meshes. • Higher load and lower displacement at failure for the protection system including plaster. Reinforced concrete and brick composite floors are typical features of Italian buildings. In these floors, falling debris caused by the detachment of non-structural parts - such as portions of brick, plaster, or concrete joist cover - is quite frequent. To prevent injuries to people and economic losses due to property damage, nowadays public authorities and companies invest considerable resources to install fall protection systems on existing floors. In this context, the present work is addressed to the experimental investigation of the performance and failure mechanism of anti-falling protection systems composed of galvanised electro-welded steel wire meshes attached to the intrados of the slab. Tests are performed under quasi-static concentrated loads up to failure. Two configurations of the protection system are analysed: with and without the presence of plaster. Experimental findings show that: (i) the electro-welded steel wire mesh can withstand considerable load up to failure (ii) the application of plaster layer modifies the failure mode and considerably increases the load-bearing capacity and the stiffness of the system. Based on the experimental investigation, the study: (i) experimentally confirms the effectiveness of this method as an anti-fall system, and (ii) provides information about the behaviour of the system that is essential for its modelling. [ABSTRACT FROM AUTHOR]

Effective reinforcing method is of great significance to the 3D concrete printing (3DCP) technology for structural application. Currently available reinforcing measures for 3DCP only provide directional instead of integral reinforcement for 3D printed constructs. To this gap, in this study, a novel reinforcing approach for 3DCP via U-type steel wire mesh (USWM) is proposed, which facilitate integrated horizontal and vertical reinforcements. Printed specimens without reinforcement, with flat steel wire mesh (FSWM) and USWM are manufactured to demonstrate the structural superiority of the currently proposed strengthening approach through flexural tests. The results show that the flexural performance of 3D printed specimens is substantially improved due to introduction of USWM, as indicated by significantly higher load-bearing capacity and deflection hardening compared to the counterparts reinforced with FSWM and plain specimen. [ABSTRACT FROM AUTHOR]

• Experimental study was performed on the flexural behavior of RC beams strengthened withthe HSSSWR meshes reinforced ECC. • Effects of various parameters on the behavior of the strengthened beams were revealed. • The calculation models were proposed to predict the flexural capacity and stiffness for the strengthened beams. In this study, the flexural behavior of reinforced concrete (RC) beams strengthened with high-strength stainless steel wire rope (HSSSWR) meshes reinforced Engineered Cementitious Composite (ECC) was investigated. In total, six strengthened beams and one control beam were manufactured and tested taking into account of test variables including the reinforcement ratio of longitudinal HSSSWR, nominal diameter of HSSSWR, and formula of ECC. The test results showed that the flexural capacity, ductility, stiffness, and toughness of the strengthened beams were sufficiently improved, and the development of crack including maximum width and spacing was delayed by using the strengthening system of HSSSWR meshes reinforced ECC, and the failure mode of the strengthened beams was concrete crushing, which was followed by the local debonding along the interface and rupture of reinforcement layer except for the beam with the relatively high reinforcement ratio of longitudinal HSSSWRs. The calculation models with high accuracy were proposed to predict the flexural capacity and stiffness for the RC beams strengthened by the HSSSWR meshes reinforced ECC, which were verified by test results in this study and existing study. [ABSTRACT FROM AUTHOR]

External confinement using jackets can suitably increase the strength and ductility of the reinforced concrete cylindrical columns. This paper encompasses an experimental investigation for studying the effectiveness and suitability of self compacting concrete (SCC) mixes as a retrofitting material and its use as jacket for cylindrical columns. The experimental programme included development of SCC mix and its use in retrofitting of cylindrical column specimens which were either intact or distressed earlier to certain level. The experimental programme consisted of testing 6 control specimens, and 36 primary specimens initially distressed to 80–85% of theoretical stress level, repairing, and retrofitting prior to testing. The control specimens were of diameter 160 mm and height 600 mm, cast in M20 conventionally vibrated concrete, reinforced longitudinally with six bars of 12 mm diameter and five lateral ties of 8 mm diameter as transverse reinforcement. Two different SCC mixes, were used for jacketing around the columns. The jacket was reinforced with mild steel welded wire mesh (WWM) 25 mm × 25 mm made of 3 mm diameter wire. The retrofitted specimens were tested after 28 days, 56 days and 90 days of curing. The test results revealed the effective use of SCC as retrofitting material. The SCC jacket with WWM as reinforcement increases the ultimate load carrying capacity of column specimen. The ductility factor is also calculated after the retrofitting with SCC mixes. [ABSTRACT FROM AUTHOR]

In this research work, the flexural behaviour of reinforced concrete (RC) beams strengthened with a new type of strengthening material, namely wire mesh-epoxy composite, was investigated. The flexural behaviour of RC beams strengthened using this new material was compared with RC beams strengthened with carbon fibre reinforced polymer (CFRP) sheet. In addition, the structural performance of a beam strengthened using a hybrid of wire mesh-epoxy and CFRP sheet was investigated. The results showed that the use of wire mesh-epoxy composite provides considerable enhancement in the performance of strengthened beams. Compared to CFRP, the wire mesh-epoxy strengthened beams showed more improvement in the first crack load, stiffness and yield strength. In addition, the use of hybrid wire mesh-epoxy-carbon fibre composite indicated better post-yield behaviour and prevented the debonding of the CFRP sheet. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the axial behavior of ferrocement confined cylindrical concrete specimens. The present study also intends to investigate the effect of specimen size on the confinement action of ferrocement jacket. Three types of 27 concrete cylinders with diameters of 150, 100, and 75 mm are cast and tested under axial compression. Each type of specimens is confined with single layer and double layer welded wire mesh ferrocement jacket having a constant thickness of the jacket. The experimental results demonstrate the effectiveness of ferrocement confinement in enhancing the strength, ductility and energy absorption capacity of concrete specimens. The confinement action is found more effective in case of smaller specimens. A post-peak descending branch in the axial stress–strain curve is observed in all the confined specimens. The stress–strain behavior and the failure pattern indicate that single layer mesh ferrocement jacket cannot provide significant confinement; at-least two layer mesh is required for substantial confinement. A new analytical model for the strength of ferrocement confined circular concrete specimen is proposed based on the test results of this work and verified with the recent experimental data obtained from the literature. [ABSTRACT FROM AUTHOR]

• Adding wire mesh in ECC substantially enhanced strength and crack control. • The average crack spacing decreased with a smaller wire and larger mesh content. • The use of a larger wire diameter led to more pronounced tension stiffening effect. • The flexural models reasonably predicted the flexural strength of ECC ferrocement. • Sensitivity of ECC compressive strain on accuracy of flexural models was studied. Ferrocement is a type of thin walls constructed of hydraulic cement mortar reinforced with closely spaced layers of wire mesh. Although the applications of ferrocement have been common, there has been a limited number of studies on the development of new ferrocement composites. Particularly, premature failure could occur to ferrocement due to the vulnerability of spalling and delamination. Engineered cementitious composite (ECC) is characterized by its ductile strain-hardening behavior and crack width control under direct tension. To enhance the mechanical properties and crack width control of ferrocement, the potential for using ECC to replace cement mortar in conventional ferrocement, termed ECC ferrocement, was explored. The influences of the volume fraction, wire size, and wire spacing of the steel mesh on the mechanical properties of ECC ferrocement under tension and flexure were studied. It was found that while ECC ferrocement had substantially enhanced strength and crack width control compared to pure ECC and conventional ferrocement, there was a relatively limited improvement in the deformation capacity. The test results also showed that the interaction between the embedded steel mesh and the surrounding ECC led to a pronounced tension stiffening effect, which significantly enhanced the uniaxial and flexural strengths of ECC ferrocement. In addition to the experimental study, three flexural models, including a rigorous implicit model and two simplified explicit models, were proposed to evaluate the flexural strength of ECC ferrocement. The comparisons between the experimental results and predicted strengths demonstrated that the proposed three models can reasonably predict the flexural strength of ECC ferrocement with an average error of less than 6% when the tension stiffening of ECC was accounted for. The results of parametric studies indicated that a variation in the ultimate ECC compressive strain ranging between 0.003 and 0.005 for the flexural models led to a negligible influence on the predicted flexural strength. [ABSTRACT FROM AUTHOR]

The main objective of the present experimental program is to study the behavior of reinforced concrete short columns subjected to combined axial load and flexure strengthened with ferrocement. To carry out the investigation, seven columns were tested. Out of which, one is the control un-strengthened column tested to failure to find out their load carrying capacity, six columns strengthened with ferrocement. The main objective of the present work is to investigate the effects of ferrocement thickness and number of wire meshes on the load capacity of those columns. Increasing wire mesh layers from 2 to 5 causes an increase in the ultimate load of the strengthened column with ferrocement compared with the control column. Using 20mm ferrocement thickness with a 5-wire mesh layers, the ultimate load increases 36.8% when compared with the control column. Similarly, for 30mm ferrocement thickness with 5 wire mesh layers the increase is 48%. [ABSTRACT FROM AUTHOR]

Abstract: Conventional square ferrocement jacketing (square jacketing with single or multiple layers wire mesh) cannot provide lateral confinement effectively in restrengthening of square RC column due to stresses concentration at the column corners. Therefore, improvement of conventional square ferrocement jacketing technique is focused in this study. Three new square ferrocement jacketing techniques such as square jacketing with single layer wire mesh and rounded column corners (RSL); square jacketing using single layer wire mesh with shear keys at the center of each face of column (SKSL) and square jacketing with single layer wire mesh and two extra layers mesh at each corner (SLTL) are considered for this purpose. Entire study was carried out experimentally. A total number of 41 scaled down non-jacketed and ferrocement jacketed column specimens were tested under both concentric and eccentric modes of loading. Test results and the crack patterns of tested specimens show that all three improved square ferrocement jacketing techniques are effective to overcome the stress concentration problem of conventional square ferrocement jacketing. Among all jacketing techniques considered in this study SLTL type jacketing shows the best performance in carrying concentric loading, however, in case of eccentric loading, best performance is found in RSL type ferrocement jacketing. [Copyright &y& Elsevier]

Following a brief history and definition, this paper focuses on the evolution, mostly over the past five decades, of ferrocement and thin cement-based composites which are defined here as having less than about 50 mm in thickness. Although conventional reinforcements for these products are steel wire meshes or metal lath, new forms of reinforcements have emerged over the years with the objective of improving performance and minimizing total product cost. They include: (1) fiber reinforced polymeric (FRP) reinforcements (or textiles or fabrics) which use high performance fibers, such as carbon, Kevlar, Spectra and the like, (2) new steel unidirectional reinforcing mats made with extremely high strengths wires or strands, (3) 3D textiles or fabrics using polymeric fibers, (4) 3D textiles using combination of polymeric fibers and steel, and (5) reinforcement using shape-memory materials to induce self-stressing. Over the same period, the cement matrix has evolved enormously in its compressive strength and durability properties in the hardened state, and flow ability and ease of casting in the fresh state leading to new qualifications such as high strength or high performance, ultra high strength or ultra high performance, self-consolidating and self-compacting, etc. Adding fibers or micro-fibers to the cement matrix of ferrocement adds another dimension to the resulting composite as well as potential for improved performance. After describing the limits so far achieved using the above materials, the paper presents the current challenges and sets the limits to exceed in future developments. [ABSTRACT FROM AUTHOR]

Abstract: An experimental study on 18 simply supported ferrocement plates having a span/depth ratio of 2.0 was conducted. Various wire mesh types were used as web reinforcement. Flexural steel was designed to preclude failure in modes other than flexure. Two groups, A and B, were tested under central uniform loads covering 10% and 67.5% of the clear span respectively. It was observed that, the percentage increase of shear capacity over the reference specimen is remarkable for group A and nearly equal to 40%. Moreover, a hexagonal mesh, of 0.15%, improves the shear capacity than those of diamond and square meshes of 0.25% and 0.38% volume fraction respectively. Specimens of group B demonstrate a slight increase of the ultimate shear capacity than those of group A despite that the web reinforcement is less effective as pointed out by comparing the results of each group with its associated reference specimen. A good agreement between the classical shear equations prediction and the experimental values is obtained for group A specimens whereas the ultimate shear capacity for group B is underestimated. It is also indicated that the strut and tie model is an inappropriate technique for the ferrocement plate design compared to the classical shear equations of deep beams. [Copyright &y& Elsevier]

This paper presents results of an experimental study on a method for repairing earthquake damaged reinforced concrete columns that have inadequate lap splices in longitudinal reinforcement, by the use of stainless steel wire mesh (SSWM) composites. A total of three 1/5 scale model columns were tested under reversed cyclic loading. The columns were then repaired with SSWM composite wraps and re-tested under simulated earthquake loading to validate the effectiveness of the SSWM composite system and to study the feasibility of the repairing method for damaged columns. The results of this study show that the flexural strength, the displacement ductility, and the energy dissipation of the repaired columns were higher than those of the original columns. This indicates that the SSWM composite wraps can be a highly effective repair measure for reinforced concrete columns that have inadequate lap splices. [ABSTRACT FROM AUTHOR]

One of the foremost factors affecting the durability of ferrocement is the corrosion of wire meshes. This problem is magnified in corrosive environments. With the passage of time, the effective strength of the wires is reduced due to a reduction in diameter and deterioration of the bond between the matrix and the reinforcement. In the present study, an attempt has been made to improve the corrosion resistance of the metallic wire meshes used in ferrocement with corrosion inhibitors. Two corrosion inhibitors, viz. Calcium Nitrite and Tannic Acid, were used. Weight loss studies and potentio-dynamic polarization tests were conducted in saline water medium. Corrosion efficiency and corrosion rate were calculated. At a 1% dose, both the inhibitors, when applied in a slurry coated form, were found to be sufficiently effective in controlling the corrosion. The effect of these corrosion inhibitors on setting time of cement, pH, and compressive strength of cement sand mortar were also observed. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the use of ferrocement as an external confinement to concrete specimens is investigated. The effectiveness of confinement is achieved by comparing the behavior of retrofitted specimens with that of conventional specimens. The primary test variable considered in this study is the concrete compressive strength. All the other parameters, such as size, shape, number of layers of wire mesh, and L/d ratio of the specimens, were kept constant. The sections chosen are circular cylinders with a size of 150mm×300mm and L/d ratio of 6:1. The test results showed that the confined concrete specimens can enhance the ultimate concrete compressive strengths and failure strains. [Copyright &y& Elsevier]

Abstract: The structural fire integrity performance of a ferrocement jacket was experimentally determined based on its flexural characteristics and damage after exposure to fire. The main parameters investigated were the volume fraction of wire mesh and mortar cover. A sandwich-sample configuration was adopted to simulate the actual conditions of exposure to fire in which the maximum temperature of 1060°C was reached within 3h. Tests showed that a ferrocement jacket was a satisfactory fire protection material due to its post-fire strength compared with that of plain mortar. Although an increase in wire mesh content significantly improved the mechanical properties of ferrocement under normal conditions, after fire exposure the content of wire mesh was no longer significant and higher volume fractions of wire mesh resulted in in-plane cracking. Mortar covers had negligible influence on the mechanical properties of ferrocement jackets under both normal and after fire exposures. However more visible fire damage occurred in ferrocement with thinner mortar cover. [Copyright &y& Elsevier]

In this paper, experimental and numerical studies were implemented to evaluate the effect of Crumb Rubber (CR) ratio and Welded Wire Mesh (WWM) layers on the flexural behavior of RC beams. The volume of fine aggregate was partially replaced by CR particles with three percentages (0%, 10% and 20%). One layer and two layers of the WWM with U shape were additionally added to the shear reinforcement. The test results revealed that, the replacement of fine aggregate by 10% and 20% CR decreased the load capacity of the RC beams by 3.85% and 6.15% respectively compared to that without CR. Conversely, using the WWM as shear reinforcement increased the load capacity of beams and changed beams failure from shear to flexural (steel yielding followed by concrete crushing). The load capacity of RC beams cast without CR and strengthened in shear with one and two WWM layers increased by 6.2% and 9.2% respectively over that without WWM. Moreover, there was a significant increase in the ductility index of the all beams with CR. Finally, the obtained numerical results showed a good agreement with the experimental ones indicating the ability of the numerical model to simulate the behavior of rubberized concrete. [ABSTRACT FROM AUTHOR]

The flexural test was conducted to investigate crack resistance, loading bearing capacity, deformation characteristics and failure modes of damaged reinforced concrete (RC) beams strengthened by reinforced ultra-high performance concrete (UHPC) layer (Abbreviated as UC). Also, their mechanical properties were compared with those of the unstrengthened RC beam (Abbreviated as I–C). Additionally, the effects of pre-damage degrees in the RC beams and three strategies for the improvement of toughness of the reinforced UHPC layer on the cracking and flexural performance of UC were discussed. The results showed that UC acted monolithically under flexure without interfacial debonding before typically flexural failure. Compared with I–C, cracking and ultimate loads of UC increased by 1.57–3.32 times and 1.72–2.21 times, respectively. The reinforced UHPC layer effectively suppressed the cracking of the RC beam, making crack width in the RC beam propagate slowly with the load. Moreover, the severer the pre-damage degree of the RC beam, the smaller improvement of the flexural performance of UC. The addition of steel wire mesh, orientation of steel fibers and moderate-temperature steam curing further improved the cracking and flexural performance of UC with the most evident improvement in the addition of steel wire mesh. Finally, the theoretical model and formula were proposed for the calculation of load bearing capacity of UC with consideration of the influence of the pre-damage degrees in the RC beams, and the experimental results verified that the theoretical formula can accurately predict the load bearing capacity of UC. • The flexural behavior of damaged RC beams strengthened by reinforced UHPC layer (UC) was investigated. • The effect of pre-damage degrees in the RC beams on the flexural performance of UC was discussed. • The three strategies for improvement of toughness of the reinforced UHPC layer was discussed. • The theoretical formulas were proposed for the calculation of load bearing capacity of UC with the pre-damage degrees. [ABSTRACT FROM AUTHOR]